Why is the "R" trademark symbol on Pepsi labels placed after the second "P" in "Pepsi" rather than after the words "Pepsi" or "Cola"?

It's not always after the second "P". Some instances place the registered trademark symbol after "Pepsi" or don't even include it at all. Earlier logos, specifically the script writing before 1963, placed the "circle R" below the script. Logos after 1998 place it after the word "Pepsi".

Speculation is that it was placed after the second "P" to center it within the logo and make it more visible on a bottle for advertising purposes. After all, placing it after the "I" would put it about 90° from center when viewed on a bottle and may not even be visible in photographs.

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